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प्रश्न
What is an indicator?
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उत्तर
An acid-base indicator is a chemical substance that indicates the acidic or basic nature of a solution by a suitable colour change.
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संबंधित प्रश्न
Fresh milk from cows has a pH of 6. So how does the pH change when this milk is turned to curd? Explain your answer.
A milkman adds a very small amount of baking soda to fresh milk. Why does he shift the pH of the fresh milk from 6 to slightly alkaline?
Is the distilled water acidic/basic/neutral? How would you verify it?
Acids have a ______ taste and they turn ______ litmus to ______.
Those substances whose smell (or odour) changes in acidic or basic solutions are called ______ indicators.
The pH of a cold drink is 5. What will be its action on blue and red litmus solutions?
Fresh milk has a pH of 6. When milk changes into curd, the pH value will:
(a) become 7
(b) become less than 6
(c) become more than 7
(d) remain unchanged
Here are some results of solutions tested with universal indicator paper:
| Sulphuric acid | : Red |
| Metal polish | : Dark blue |
| Washing-up liquid | : Yellow |
| Milk of magnesia | : Light blue |
| Oven cleaner | : Purple |
| Car batter acid | : Pink |
Arrange the solutions in order of their increasing pH value (starting with the one with the lowest pH).
State whether the following statement is true or false. Correct the false statement.
Phenolphthalein is a natural indicator.
Using the knowledge of acids and bases, write a secret message with the help of baking soda and beet root. Explain how it works.
(Hint: Prepare baking soda solution in water. Use this solution to write the message on a sheet of white paper with a cotton bud. Rub a slice of fresh beetroot over the message.)
